The following is based on information taken from the Cycleserv publication: Norton Commando ‘S’ Type, Roadster, Fastback (Page 66). It is based on standard gear ratios and sprockets with 19” wheels and a 4.10 section rear tyre. The only variable is the number of teeth on the gearbox sprocket. My Commando is now fitted with a 20 tooth gearbox sprocket, down from the 22 tooth sprocket with which it came. 1. Number of Gearbox Sprocket Teeth = 19 and Top Gear Ratio = 4.84:1 = 15.429 mph/1,000 revs in Top Gear (or 24.857 km/h). It = 108 mph @ 7,000 rpm. | Fourth Gear | Third Gear | Second Gear | Revs | Mph | Mph | Mph | | | | | 1,500 | 23.14 | 19.07 | 13.50 | 2,000 | 30.86 | 25.42 | 18.00 | 2,500 | 38.57 | 31.78 | 22.50 | 3,000 | 46.29 | 38.13 | 27.00 | 3,500 | 54.00 | 44.49 | 31.50 | 4,000 | 61.72 | 50.84 | 36.00 | 4,500 | 69.43 | 57.19 | 40.50 | 5,000 | 77.15 | 63.55 | 45.00 | 5,500 | 84.86 | 69.91 | 49.50 | 6,000 | 92.57 | 76.26 | 54.00 | 6,500 | 100.29 | 82.62 | 58.50 | 7,000 | 108.00 | 88.97 | 63.00 |
2. Number of Gearbox Sprocket Teeth = 20 and Top Gear Ratio = 4.60:1 = 16.286 mph/1,000 revs in Top Gear (or 26.286 km/h). It = 114 mph @ 7,000 rpm. | Fourth Gear | Third Gear | Second Gear | Revs | Mph | Mph | Mph | | | | | 1,500 | 24.43 | 20.14 | 14.35 | 2,000 | 35.57 | 26.86 | 19.14 | 2,500 | 40.72 | 33.58 | 23.93 | 3,000 | 48.86 | 40.29 | 28.72 | 3,500 | 57.00 | 47.00 | 33.50 | 4,000 | 65.14 | 53.72 | 38.28 | 4,500 | 73.29 | 60.44 | 43.07 | 5,000 | 81.43 | 67.15 | 47.86 | 5,500 | 89.57 | 73.87 | 52.64 | 6,000 | 97.72 | 80.58 | 57.43 | 6,500 | 105.86 | 87.29 | 62.21 | 7,000 | 114.00 | 94.00 | 67.00 |
3. Number of Gearbox Sprocket Teeth = 21 and Top Gear Ratio = 4.38:1 = 17.000 mph/1,000 revs in Top Gear (or 27.286 km/h). It = 119 mph @ 7,000 rpm. | Fourth Gear | Third Gear | Second Gear | Revs | Mph | Mph | Mph | | | | | 1,500 | 25.50 | 21.21 | 15.00 | 2,000 | 34.00 | 28.28 | 20.00 | 2,500 | 42.50 | 35.35 | 25.00 | 3,000 | 51.00 | 42.42 | 30.00 | 3,500 | 59.50 | 49.49 | 35.00 | 4,000 | 68.00 | 56.56 | 40.00 | 4,500 | 76.50 | 63.63 | 45.00 | 5,000 | 85.00 | 70.70 | 50.00 | 5,500 | 93.50 | 77.77 | 55.00 | 6,000 | 102.00 | 84.84 | 60.00 | 6,500 | 110.50 | 91.91 | 65.00 | 7,000 | 119.00 | 99.00 | 70.00 |
Perce Butterworth |
